The Radiation Therapy Oncology Group is a cooperative clinical group of Radiation Therapy Research Centers formed to conduct clinical investigative studies and trails in oncology. At the present time there are 19 founding member institutions, 9 full members, and 20 provisional members giving a total of 48 institutions working together on a common cooperative set of protocol projects. There are currently 10 clinical research projects being carried out by RTOG, we are participating in 7 of these. The purpose of this organization is the establishment and maintenance of a coalition of clinical Radiation Therapy Centers to develop effecient and economical means for conducting clinical trails in oncology. A coalition of centers allows the accumulation of a sufficent number of cases in a reasonable length of time. In provides a critical group to integrate new biological concepts into clinical investigative programs in radiation therapy. It is felt that there is a very definite and pressing need to improve results of radiation therapy and to create a mechanism whereby any real advances in radiation therapy can be quickly recognized and disseminated to other institutions for their eventual incorporation into routine treatment plans. This coalition of institutions provides a mechanism whereby many of the controversial problems in radiation therapy might be brought into clinical trails and a final proof of the value of various treatment measurements may eventually result.